Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Sep 10 2025 Valid 102000Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...20z Update... No changes are needed to the D1 Convective Outlook. See previous discussion below for more information. ..Thornton.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/ ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Sep 10 2025 Valid 102000Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...20z Update... No changes are needed to the D1 Convective Outlook. See previous discussion below for more information. ..Thornton.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/ ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Sep 10 2025 Valid 102000Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...20z Update... No changes are needed to the D1 Convective Outlook. See previous discussion below for more information. ..Thornton.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/ ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Sep 10 2025 Valid 102000Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...20z Update... No changes are needed to the D1 Convective Outlook. See previous discussion below for more information. ..Thornton.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/ ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Sep 10 2025 Valid 102000Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...20z Update... No changes are needed to the D1 Convective Outlook. See previous discussion below for more information. ..Thornton.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/ ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Sep 10 2025 Valid 102000Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...20z Update... No changes are needed to the D1 Convective Outlook. See previous discussion below for more information. ..Thornton.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/ ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Wed Sep 10 2025 Valid 102000Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...20z Update... No changes are needed to the D1 Convective Outlook. See previous discussion below for more information. ..Thornton.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/ ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0137 PM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE FOUR CORNERS REGION... ...SUMMARY... Isolated strong to severe storms capable of isolated large hail and severe wind gusts are possible across the Four Corners region on Friday. Additional storms are possible over the northern Plains and Upper Midwest Friday morning and Friday night. ...Synopsis... On Friday, a strong trough will begin across the Intermountain West with a trough across the Plains and a trough along the East Coast. The pattern will shift slowly east through the day. At the surface, expansive high pressure will lead to fair weather across much of the eastern CONUS with a weak lee cyclone in the central/northern Plains. ...Four Corners Region... Residual moisture within the Southwest and central Rockies will result in 500 to 1000 J/kg MLCAPE by early Friday afternoon across portions of the Southwest and into southeast Utah and western Colorado. This instability, combined with weak height falls and terrain circulations will result in widespread thunderstorm activity Friday afternoon. Moderate mid-level flow (40 to 45 knots) will result in sufficient speed shear for some organized storm potential. While instability will be overall weak, pockets of greater instability/stronger storms may result in a few isolated supercells with a threat for large hail and severe wind gusts. ...Northern Plains... A cluster of storms may be ongoing at the beginning of the period across the eastern Dakotas/western Minnesota. If this occurs, some marginal wind/hail threat could exist during the morning before the low-level jet weakens. However, there is considerable uncertainty at this time whether ongoing convection will be in place Friday morning. Additional storm coverage uncertainty exists Friday night. Most guidance is fairly consistently showing a 40 to 50 knot low-level jet across the central Plains. Moderate instability will exist across southern South Dakota and if isentropic ascent can reach this far north, some elevated strong to isolated severe storms may be possible Friday night. However, at this time there is considerable uncertainty whether this frontal zone and the low-level jet will overlap. In addition, the low-level jet remains mostly veered Friday night which will result in relatively weak isentropic ascent. Therefore, a conditional elevated hail threat may exist across South Dakota Friday night, but storm coverage remains too uncertain at this time for probabilities. ..Bentley.. 09/10/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Sep 10 2025 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES TO THE NORTHERN PLAINS.... ...SUMMARY... Isolated strong to severe thunderstorms with hail and severe wind potential are possible across portions of the Rockies, central/northern High Plains into the Dakotas and northern Minnesota on Thursday. ...Synopsis... On Thursday, a large trough will be present across the western CONUS with a strong ridge across the Plains and troughing across the east. This pattern will shift slowly east through the day. Surface high pressure will dominate much of the eastern CONUS with lee troughing in the central and northern High Plains. ...Eastern Montana/northern Wyoming into the Dakotas and northern Minnesota... A cluster of storms may be ongoing across northern North Dakota at the start of the period. A moderate low-level jet is forecast to maintain intensity (and perhaps strengthen somewhat) during the day. This may result in maintenance of this cluster and restrengthening during the afternoon across southern Canada and perhaps into northern North Dakota and northern Minnesota. Moderate instability and moderate shear, combined with steep lapse rates, will support the potential for large hail and damaging wind gusts as these storms move east. Cooling temperatures aloft and steep lapse rates will lead to scattered to widespread thunderstorm development across much of the higher terrain across Wyoming and Montana. Modest deep-layer shear and a relatively dry profile will support the potential for some organized storms including supercells. These storms may produce isolated large hail and severe wind gusts. A more conditional severe environment will be present across eastern Wyoming/Montana and into the western Dakotas. Stronger instability (2000 to 3000 J/kg MLCAPE) is forecast across the region, but only weak height falls will be present with at least some residual capping from most forecast soundings. Some weak convergence/confluence will be present along the lee trough/dryline which could initiate a few storms. If storm form within this region, moderate deep-layer shear could support supercells capable of large hail and severe wind gusts. If this scenario appears more likely, a Slight Risk may be needed in later outlooks, particularly across eastern Montana and western North Dakota. ...Central Rockies... Moderate to strong shear will be present across the Rockies as a 45 to 60 knot mid-level jet streak overspreads the region. Weak height falls, terrain driven circulations, and weak diffluence aloft will combine for widespread thunderstorm development Thursday afternoon/evening. RAP forecast soundings show 500 to 750 J/kg MLCAPE and 1000-1300 J/kg MUCAPE at KGJT which is well above the 90th percentile and near the all time maximum for mid-September in GJT based on SPC sounding climatology. This abnormally unstable airmass combined with moderate shear will result in an environment capable of a few weak supercells producing isolated large hail and severe wind gusts across eastern Utah, the Four Corners region, much of Colorado, and southern Wyoming. ..Bentley.. 09/10/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Sep 10 2025 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES TO THE NORTHERN PLAINS.... ...SUMMARY... Isolated strong to severe thunderstorms with hail and severe wind potential are possible across portions of the Rockies, central/northern High Plains into the Dakotas and northern Minnesota on Thursday. ...Synopsis... On Thursday, a large trough will be present across the western CONUS with a strong ridge across the Plains and troughing across the east. This pattern will shift slowly east through the day. Surface high pressure will dominate much of the eastern CONUS with lee troughing in the central and northern High Plains. ...Eastern Montana/northern Wyoming into the Dakotas and northern Minnesota... A cluster of storms may be ongoing across northern North Dakota at the start of the period. A moderate low-level jet is forecast to maintain intensity (and perhaps strengthen somewhat) during the day. This may result in maintenance of this cluster and restrengthening during the afternoon across southern Canada and perhaps into northern North Dakota and northern Minnesota. Moderate instability and moderate shear, combined with steep lapse rates, will support the potential for large hail and damaging wind gusts as these storms move east. Cooling temperatures aloft and steep lapse rates will lead to scattered to widespread thunderstorm development across much of the higher terrain across Wyoming and Montana. Modest deep-layer shear and a relatively dry profile will support the potential for some organized storms including supercells. These storms may produce isolated large hail and severe wind gusts. A more conditional severe environment will be present across eastern Wyoming/Montana and into the western Dakotas. Stronger instability (2000 to 3000 J/kg MLCAPE) is forecast across the region, but only weak height falls will be present with at least some residual capping from most forecast soundings. Some weak convergence/confluence will be present along the lee trough/dryline which could initiate a few storms. If storm form within this region, moderate deep-layer shear could support supercells capable of large hail and severe wind gusts. If this scenario appears more likely, a Slight Risk may be needed in later outlooks, particularly across eastern Montana and western North Dakota. ...Central Rockies... Moderate to strong shear will be present across the Rockies as a 45 to 60 knot mid-level jet streak overspreads the region. Weak height falls, terrain driven circulations, and weak diffluence aloft will combine for widespread thunderstorm development Thursday afternoon/evening. RAP forecast soundings show 500 to 750 J/kg MLCAPE and 1000-1300 J/kg MUCAPE at KGJT which is well above the 90th percentile and near the all time maximum for mid-September in GJT based on SPC sounding climatology. This abnormally unstable airmass combined with moderate shear will result in an environment capable of a few weak supercells producing isolated large hail and severe wind gusts across eastern Utah, the Four Corners region, much of Colorado, and southern Wyoming. ..Bentley.. 09/10/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Sep 10 2025 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES TO THE NORTHERN PLAINS.... ...SUMMARY... Isolated strong to severe thunderstorms with hail and severe wind potential are possible across portions of the Rockies, central/northern High Plains into the Dakotas and northern Minnesota on Thursday. ...Synopsis... On Thursday, a large trough will be present across the western CONUS with a strong ridge across the Plains and troughing across the east. This pattern will shift slowly east through the day. Surface high pressure will dominate much of the eastern CONUS with lee troughing in the central and northern High Plains. ...Eastern Montana/northern Wyoming into the Dakotas and northern Minnesota... A cluster of storms may be ongoing across northern North Dakota at the start of the period. A moderate low-level jet is forecast to maintain intensity (and perhaps strengthen somewhat) during the day. This may result in maintenance of this cluster and restrengthening during the afternoon across southern Canada and perhaps into northern North Dakota and northern Minnesota. Moderate instability and moderate shear, combined with steep lapse rates, will support the potential for large hail and damaging wind gusts as these storms move east. Cooling temperatures aloft and steep lapse rates will lead to scattered to widespread thunderstorm development across much of the higher terrain across Wyoming and Montana. Modest deep-layer shear and a relatively dry profile will support the potential for some organized storms including supercells. These storms may produce isolated large hail and severe wind gusts. A more conditional severe environment will be present across eastern Wyoming/Montana and into the western Dakotas. Stronger instability (2000 to 3000 J/kg MLCAPE) is forecast across the region, but only weak height falls will be present with at least some residual capping from most forecast soundings. Some weak convergence/confluence will be present along the lee trough/dryline which could initiate a few storms. If storm form within this region, moderate deep-layer shear could support supercells capable of large hail and severe wind gusts. If this scenario appears more likely, a Slight Risk may be needed in later outlooks, particularly across eastern Montana and western North Dakota. ...Central Rockies... Moderate to strong shear will be present across the Rockies as a 45 to 60 knot mid-level jet streak overspreads the region. Weak height falls, terrain driven circulations, and weak diffluence aloft will combine for widespread thunderstorm development Thursday afternoon/evening. RAP forecast soundings show 500 to 750 J/kg MLCAPE and 1000-1300 J/kg MUCAPE at KGJT which is well above the 90th percentile and near the all time maximum for mid-September in GJT based on SPC sounding climatology. This abnormally unstable airmass combined with moderate shear will result in an environment capable of a few weak supercells producing isolated large hail and severe wind gusts across eastern Utah, the Four Corners region, much of Colorado, and southern Wyoming. ..Bentley.. 09/10/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Sep 10 2025 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES TO THE NORTHERN PLAINS.... ...SUMMARY... Isolated strong to severe thunderstorms with hail and severe wind potential are possible across portions of the Rockies, central/northern High Plains into the Dakotas and northern Minnesota on Thursday. ...Synopsis... On Thursday, a large trough will be present across the western CONUS with a strong ridge across the Plains and troughing across the east. This pattern will shift slowly east through the day. Surface high pressure will dominate much of the eastern CONUS with lee troughing in the central and northern High Plains. ...Eastern Montana/northern Wyoming into the Dakotas and northern Minnesota... A cluster of storms may be ongoing across northern North Dakota at the start of the period. A moderate low-level jet is forecast to maintain intensity (and perhaps strengthen somewhat) during the day. This may result in maintenance of this cluster and restrengthening during the afternoon across southern Canada and perhaps into northern North Dakota and northern Minnesota. Moderate instability and moderate shear, combined with steep lapse rates, will support the potential for large hail and damaging wind gusts as these storms move east. Cooling temperatures aloft and steep lapse rates will lead to scattered to widespread thunderstorm development across much of the higher terrain across Wyoming and Montana. Modest deep-layer shear and a relatively dry profile will support the potential for some organized storms including supercells. These storms may produce isolated large hail and severe wind gusts. A more conditional severe environment will be present across eastern Wyoming/Montana and into the western Dakotas. Stronger instability (2000 to 3000 J/kg MLCAPE) is forecast across the region, but only weak height falls will be present with at least some residual capping from most forecast soundings. Some weak convergence/confluence will be present along the lee trough/dryline which could initiate a few storms. If storm form within this region, moderate deep-layer shear could support supercells capable of large hail and severe wind gusts. If this scenario appears more likely, a Slight Risk may be needed in later outlooks, particularly across eastern Montana and western North Dakota. ...Central Rockies... Moderate to strong shear will be present across the Rockies as a 45 to 60 knot mid-level jet streak overspreads the region. Weak height falls, terrain driven circulations, and weak diffluence aloft will combine for widespread thunderstorm development Thursday afternoon/evening. RAP forecast soundings show 500 to 750 J/kg MLCAPE and 1000-1300 J/kg MUCAPE at KGJT which is well above the 90th percentile and near the all time maximum for mid-September in GJT based on SPC sounding climatology. This abnormally unstable airmass combined with moderate shear will result in an environment capable of a few weak supercells producing isolated large hail and severe wind gusts across eastern Utah, the Four Corners region, much of Colorado, and southern Wyoming. ..Bentley.. 09/10/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Sep 10 2025 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES TO THE NORTHERN PLAINS.... ...SUMMARY... Isolated strong to severe thunderstorms with hail and severe wind potential are possible across portions of the Rockies, central/northern High Plains into the Dakotas and northern Minnesota on Thursday. ...Synopsis... On Thursday, a large trough will be present across the western CONUS with a strong ridge across the Plains and troughing across the east. This pattern will shift slowly east through the day. Surface high pressure will dominate much of the eastern CONUS with lee troughing in the central and northern High Plains. ...Eastern Montana/northern Wyoming into the Dakotas and northern Minnesota... A cluster of storms may be ongoing across northern North Dakota at the start of the period. A moderate low-level jet is forecast to maintain intensity (and perhaps strengthen somewhat) during the day. This may result in maintenance of this cluster and restrengthening during the afternoon across southern Canada and perhaps into northern North Dakota and northern Minnesota. Moderate instability and moderate shear, combined with steep lapse rates, will support the potential for large hail and damaging wind gusts as these storms move east. Cooling temperatures aloft and steep lapse rates will lead to scattered to widespread thunderstorm development across much of the higher terrain across Wyoming and Montana. Modest deep-layer shear and a relatively dry profile will support the potential for some organized storms including supercells. These storms may produce isolated large hail and severe wind gusts. A more conditional severe environment will be present across eastern Wyoming/Montana and into the western Dakotas. Stronger instability (2000 to 3000 J/kg MLCAPE) is forecast across the region, but only weak height falls will be present with at least some residual capping from most forecast soundings. Some weak convergence/confluence will be present along the lee trough/dryline which could initiate a few storms. If storm form within this region, moderate deep-layer shear could support supercells capable of large hail and severe wind gusts. If this scenario appears more likely, a Slight Risk may be needed in later outlooks, particularly across eastern Montana and western North Dakota. ...Central Rockies... Moderate to strong shear will be present across the Rockies as a 45 to 60 knot mid-level jet streak overspreads the region. Weak height falls, terrain driven circulations, and weak diffluence aloft will combine for widespread thunderstorm development Thursday afternoon/evening. RAP forecast soundings show 500 to 750 J/kg MLCAPE and 1000-1300 J/kg MUCAPE at KGJT which is well above the 90th percentile and near the all time maximum for mid-September in GJT based on SPC sounding climatology. This abnormally unstable airmass combined with moderate shear will result in an environment capable of a few weak supercells producing isolated large hail and severe wind gusts across eastern Utah, the Four Corners region, much of Colorado, and southern Wyoming. ..Bentley.. 09/10/2025 Read more